Welcome to the forum!
I've been reading this post for awhile now and, I have to say that you're one step away from solving the problem...
Change the faulty regulator & recheck for any other leaks that might appear after the new regulator is installed just for good measure.
On another note; Your instructor may well be knowledgable enough to teach but, I do'nt agree with his comments regarding the GTAW process! I must concurr with Lawrence that thi$ proce$$ i$ well worth becoming proficient in... Heck, I know a few good welders out there that I know for a fact are anything but, what your instructor referred to so, learn as much as you can about this process because, later on in your career, you'll be glad that you did... Btw, It's always good to read your comments Larry!!! I hope everything is well and all the best!!!
Anywho, Buono fortuno (good fortune or some people mean good luck) and keep practicing so that when you become tired, you practice some more!!! Most important of all,
Never stop learning and, never stop seeking to learn more because, a true craftsman or craftsperson, is always seeking more knowledge in order to improve their skill sets and always remains teachable.
Respectfully,
SSBN727 Run Silent... Run Deep!!!